Alpha is considered the highest level at present.
Beta is considered to be an exceptional mutant.
Gamma is considered to be an average mutant.
For this world, this system was created by Xavier. When some mutants reach the point that they blow Alphas out of the water, then the Omega Level will be created. The fifth class, Delta Level wouldn't usually be used by Xavier as he doesn't consider any mutant to be a "subpar mutant" unless he was simply describing a mutant who lacks training or a basic understanding of their state, but someone like Apocalypse or Mr. Sinsiter would definitely use that term to denote the mutants who have "pitiful abilities" or severe deformities and little power to go with it, or just use it as an insult for any mutant with less power than themselves.
As I commented in Phil's submission of the full picture, I love how you managed to re-imagine her appearance. Scarlet Witch's design is something I would consider quite a low point of her character, being eye-candy and little else to transmit her character identity through her costume or general clothes.- But you made an amazing work here to give her a distinctive look.